When dilute sodium chloride is electrolysed using graphite electrodes, which cation is discharged at the cathode most readily?

Options

A. `Na^(+)`
B. `OH^(-)`
C. `H^(+)`
D. `Cl^(-)`

Explanation

To determine which cation is discharged at the cathode most readily during the electrolysis of dilute sodium chloride using graphite electrodes, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Electrolytic Cell Setup**:
- In an electrolytic cell, we have two electrodes: an anode (positive) and a cathode (negative). The sodium chloride solution is placed in the container, and an external battery is connected to these electrodes.

2. **Understand Ion Migration**:
- In the solution, the cations (positively charged ions) will migrate towards the cathode (negative electrode) for discharge. In the case of dilute sodium chloride, the cations present are Na⁺ (sodium ions) and H⁺ (hydrogen ions from water).

3. **Identify the Cations**:
- The two cations that can be discharged at the cathode are Na⁺ and H⁺. We need to determine which of these will be discharged more readily.

4. **Refer to the Electrochemical Series**:
- To compare the discharge potentials of the cations, we refer to the electrochemical series, which lists the standard reduction potentials of various ions.

5. **Compare Standard Reduction Potentials**:
- The standard reduction potential for Na⁺ is significantly lower than that for H⁺. This means that H⁺ has a higher tendency to gain electrons (be reduced) compared to Na⁺.

6. **Conclusion**:
- Since H⁺ has a higher standard reduction potential, it will be discharged at the cathode more readily than Na⁺. Therefore, the cation that is discharged at the cathode most readily is H⁺.

### Final Answer:
The cation that is discharged at the cathode most readily during the electrolysis of dilute sodium chloride is **H⁺ (hydrogen ion)**.